This invention relates to a gasoline internal combustion (IC) engine, and more particularly to a two-stroke engine having reduced hydrocarbon emissions.
As is well known to those skilled in this art, a two-stroke engine develops more power than a four-stroke engine of the same displacement, but the prior art two-stroke engines have the disadvantage of producing greater hydrocarbon emissions. The hydrocarbon emissions are due in part to incomplete combustion of the fuel-oil-air mixture and in part to a loss of some of the fresh mixture or charge during the scavenging part of the operating cycle. During scavenging both the inlet port and the exhaust port are open at the same time, and the fresh mixture flows into the combustion chamber and sweeps the burned gases out through the exhaust port. Unfortunately, some of the fresh mixture also passes through the exhaust port, thereby producing the above-mentioned hydrocarbon emissions. The foregoing operation is described in more detail hereinafter in connection with FIG. 1 of the drawings.
It is a general object of the present invention to provide an improved two-stroke engine which substantially reduces the quantity of hydrocarbon emissions.